Abstracts now available online - Euro Fed Lipid

Fungal sphingolipids as targets of plant defense reactions
Petra Sperling 1 , Sandra Albrecht 1 , Philipp Ternes 1 , Karin Thevissen 2 , Ulrich Zähringer 3 ,
Dirk Warnecke 1 , Bruno P. A. Cammue 2 and Ernst Heinz 1
1
Biocenter Klein Flottbek and Botanical Garden, University of Hamburg, Hamburg,
Germany; 2 Center of Microbial and Plant Genetics, Catholic University of Leuven,
Heverlee, Belgium; 3 Research Center Borstel, Borstel, Germany
In eukaryotic cells, sphingolipids have become a focus of interest, because they are
involved in signal transduction pathways and other cellular processes.
Glucosylceramide (GlcCer) represents the unique glycosphingolipid which plants, fungi
and animals have in common. On the other hand, organism-specific modifications occur
at the ceramide backbone of GlcCer. While plants possess a large variety of different,
mainly delta 8-(Z)-unsaturated GlcCers, most fungi share a consensus GlcCer structure
which is characterized by (4E,8E)-9-methylsphinga-4,8-dienine linked to a saturated or
monounsaturated alpha-hydroxy fatty acid.
Recently, we have shown that fungal GlcCers act as targets for plant defensins, which
induce fungal growth arrest by plasma membrane permeabilization through specific
interaction with high affinity binding sites on fungal cells (Thevissen et al., 2004, JBC
279: 3900-3905). The structural features of fungal GlcCer which contribute to the
recognition by antifungal peptides, are presently unknown. To study this question, we
cloned several fungal genes enabling specific manipulations of the GlcCer structure
from Pichia pastoris. In situ engineering of the GlcCer structure by generating P.
pastoris mutants lacking either glucosylation, desaturation, hydroxylation or methylation
shows that the absence of some of these structural modifications affects the recognition
by an antifungal peptide isolated from radish seeds.